Along with the development of the antenna technology, a multi-band antenna device is provided. Referring to FIG. 1, a schematic diagram of a conventional multi-band antenna device 1300 is shown. The multi-band antenna device 1300 includes an antenna 1310, a switch 1320, a plurality of filter 1330, a switch 1340, a low-noise amplifier (LNA) 1350 and a transceiver 1360.
In an amplifier circuit module M13 composed of the switch 1340 and the LNA 1350, the efficiency of the multi-band antenna device 1300 is affected by noise figure. The lower the noise figure is, the higher the efficiency of the multi-band antenna device 1300 is. Researchers are now working on how to effectively bring down the noise figure of the amplifier circuit module M13.